.signinContainer {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
  min-height: 100%;
}

.signinCard {
  width: 100%;
  width: 450px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: var(--shadow-xl);
  padding: 2.5rem;
  position: relative;
  animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-20px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.signinHeader {
  text-align: center;
  margin-bottom: 2rem;
}

.signinTitle {
  font-size: 1.875rem;
  font-weight: 700;
  color: var(--foreground);
  margin: 0 0 0.5rem 0;
}

.signinSubtitle {
  font-size: 0.875rem;
  color: var(--foreground-tertiary);
  margin: 0;
}

.signinForm {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.formGroup {
  display: flex;
  flex-direction: column;
}

.errorMessage {
  padding: 0.75rem;
  background-color: #fef2f2;
  border: 1px solid #fecaca;
  border-radius: 6px;
  color: #dc2626;
  font-size: 0.875rem;
  text-align: center;
}

.termsGroup {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.termsCheckbox {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  font-size: 0.875rem;
  color: var(--foreground-tertiary);
  cursor: pointer;
  line-height: 1.5;
  transition: color 0.2s ease;
}

.termsCheckbox:hover {
  color: var(--foreground);
}

.termsCheckbox input[type="checkbox"] {
  width: 1rem;
  height: 1rem;
  border: 1px solid var(--border);
  border-radius: 4px;
  cursor: pointer;
  margin-top: 0.125rem;
  flex-shrink: 0;
  transition: all 0.2s ease;
}

.termsCheckbox input[type="checkbox"]:checked {
  background-color: var(--primary);
  border-color: var(--primary);
}

.termsLink {
  background: none;
  border: none;
  color: var(--primary);
  cursor: pointer;
  text-decoration: none;
  padding: 0;
  margin: 0 0.25rem;
  font-size: inherit;
  transition: all 0.2s ease;
}

.termsLink:hover {
  text-decoration: underline;
  color: var(--primary-hover);
}

.termsError {
  font-size: 0.75rem;
  color: var(--destructive);
  margin-left: 1.75rem;
}

.signinButton {
  width: 100%;
  margin-top: 0.5rem;
  transition: all 0.2s ease;
}

.signinButton:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.loginPrompt {
  text-align: center;
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  font-size: 0.875rem;
  color: var(--foreground-tertiary);
}

.loginLink {
  background: none;
  border: none;
  color: var(--primary);
  cursor: pointer;
  text-decoration: none;
  font-weight: 500;
  margin-left: 0.25rem;
  transition: all 0.2s ease;
}

.loginLink:hover {
  text-decoration: underline;
  color: var(--primary-hover);
}

/* 响应式设计 */
@media (max-width: 480px) {
  .signinContainer {
    padding: 0.5rem;
  }
  
  .signinCard {
    padding: 1.5rem;
    max-width: none;
  }
  
  .signinTitle {
    font-size: 1.5rem;
  }
  
  .signinForm {
    gap: 1.25rem;
  }
  
  .termsCheckbox {
    font-size: 0.8rem;
  }
}

/* 表单验证状态样式 */
.formGroup:has(input:invalid:not(:placeholder-shown)) {
  animation: shake 0.3s ease-in-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  75% { transform: translateX(5px); }
}
